The present invention relates to the construction of an underground chamber positioned along a deep bore hole within the earth. Such chambers are often used as access work chambers at the bottom of drilled holes particularly when operating in a surrounding environment in the earth of tar sands and oil sands where there is a tremendous tendency for the earth to cave in due to a relatively large implosion pressure.
Such underground chambers for many years have been constructed by sinking a casing within the hole that is formed and then lowering workmen into the casing for cutting through such casing and carving out a chamber within the ground. The workmen then line the chamber with a material, such as a concrete material, for strengthening the chamber and making it waterproof. Such a procedure is both extremely expensive due to the extensive manual labor required as well as being extremely dangerous due to the inherent dangers of working underground, especially in an unlined and relatively unsupported chamber.
Several other techniques have been attempted for constructing underground lined chambers for various purposes. Three such techniques are disclosed in the following U.S. Pat. Nos. 3,191,309 to Schutte; 3,365,894 to Murati; and, 3,559,409 to Johnson.
The patent to Schutte discloses a procedure for use in constructing foundation members below the earth's surface, in particular where the subsurface is such that it is difficult or impossible to maintain a bore wall when drilling a bore hole for the foundation member being constructed. In the procedure set forth by such patent, the bore hole is first drilled in the surface, with the bore hole being filled with mud or other liquid during the drilling operation. Concrete is then mixed with such mud or liquid after the drilling of the hole and then a new hole is drilled in the concrete and mud mixture once the mixture has sufficiently hardened. The new hole is smaller in diameter than the original drilled bore hole so that a retaining wall of the hardened mixture of concrete and mud remains in the hole in order to prevent collapsing of the wall of the hole at least for a sufficient period of time until the foundation material itself can be poured into the hole. Once the bore hole with a bell-shaped bottom portion lined with the concrete and mud mixture is formed, the hole is then filled with the concrete for forming the foundation member.
The patent to Murati discloses a procedure for constructing caissons in a non-cohesive water-permeated ground subsurface environment. In accordance with the construction procedure set forth by such patent a bore hole is initially drilled within the earth. A water tight liner then is forced into the bore hole for supporting the walls of the hole. Next a laterally enlarged bell-shaped cavity is reamed out below the liner. The cavity is subsequently sealed off. A freezant is fed under pressure through the seal into the cavity. This freezant serves a dual purpose of forcing evacuation of any fluid in the cavity upwardly through a conduit passing through the seal and also freezes the walls of the cavity. The cavity and the bore hole are then filled with a water impermeable material such as concrete.
The patent to Johnson discloses a procedure for the construction of an underreamed and integrally grouted underground cavity. In accordance with such construction procedure, a bore hole is first drilled in the earth and a casing is located within such hole. The space between the casing and the bore hole is filled with a grout material and subsequently a larger bore hole cavity is formed in an underreaming procedure beneath the grout. This larger underreamed bore hole is then filled with additional grout material. Finally a small bore hole is drilled from the casing through the additional grout material and in a subsequent underreaming process another bore hole is formed so as to leave a cavity lined with a wall of grout material.
The following U.S. patents each show various techniques for lining bore holes or producing caissons in a drilled hole: U.S. Pat. Nos. 3,100,381 to Case et al.; 3,295,327 to Waterman; and, 3,293,865 to Loofbourow et al. U.S. Pat. No. 2,708,973 illustrates a procedure for bridging fissures or cavities encountered during the drilling of wells utilizing a cement material for sealing off such fissures or cavities. U.S. Pat. No. 3,874,733 to Poundstone et al. discloses one particular type of system for forming an underground belled shaped cavity.
Various techniques and equipment for drilling a bore hole shaft are disclosed in commonly assigned U.S. patent application Ser. Nos. 134,296, filed Mar. 26, 1980 and entitled Bore Hole Mining, and 303,511, filed Sept. 18, 1981 and entitled Blind Shaft Drilling. Various procedures for lining the bore hole shaft itself with concrete liners are disclosed in commonly assigned U.S. patent application Ser. Nos. 165,384, filed July 3, 1980 and entitled Mine Shaft Liner, and 285,815, filed July 22, 1981 and entitled Concrete Lining of Drilled Shaft.